This invention generally relates to tools and methods for removing a rivet after it has been installed, and more specifically relates to a rivet removal tool and method which eliminates, or at least substantially reduces, the end load which must be applied to drill out a button and remove a rivet.
Self-piercing rivets are used in many different applications in order to secure two or more work pieces together. When a self-piercing rivet is installed, it is pushed into engagement with the work pieces such that a portion of the rivet expands and the work pieces deform around the expanded portion of the rivet. The expanded portion of the rivet becomes effectively embedded or encapsulated in the work pieces, thereby securing the work pieces together. The deformation of the work pieces causes a protrusion, often referred to as a “button”, to form on the other side (i.e. the blind side) of the rivet, and the button includes the expanded portion of the rivet therein.
Sometimes, it is desirable to remove a rivet after it has been installed. One example is when the work pieces have become misaligned, such as during the riveting process. Prior art practices of removing a rivet after it has been installed involve initially grinding off the button. Attempting to remove a rivet by first grinding of the button is undesirable for several reasons. The grinding operation often requires that a relatively substantial end load be applied to the button (i.e. to the grinder which engages the button). This may be very difficult to achieve in light of the position of the rivet and the particular application. Even if it is possible to grind off the rivet, it becomes very difficult to push out the rivet because of the uneven ground surface. Lining up of a push out tool to the ground rivet is done by sight, which may be difficult if the rivet is in a position that is hard to see. This may also distort the hole if not lined up properly making it less likely to put a rivet back in the hole. Additionally, if the grinder slips during the grinding, it may mar the work piece. Finally, the grinding causes dust to spray into the air. This is undesirable and may create a workplace hazard, especially if the dust which sprays into the air is toxic.